Returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.

My addendum:If str1 and str2 are not equal, and str1 is a sub-string of str2 or vise versa. The returned int value will be negative or positive indicating how many characters the difference is between the two strings in absolute terms.

Example:

<?php$str1 = "phpaaa";$str2 = "php";

echo strcmp($str1, $str2); // 3?>

since str2 = "php" is a sub-string of str1 = "phpaaa" and "phpaaa" is greater than "php" the returned value is positive and is 3 indicating how many characters the difference is between the two strings.

If you replace the value of str1 with str2 the result will be -3 (negative) but still indicates the absolute difference which is 3